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Study: Benefits of Some Genetically Engineered Seeds Extend Beyond Pest Control

Amy Mayer
IPR file photo
The majority of corn, soybeans and cotton grown in the United States comes from genetically modified seeds.

After more than 20 years, an early tool of genetic engineering in crops is doing more than just killing pests. It’s providing environmental benefits, too, according to a new study in the journal Biological Control.

Genetically engineered seeds inserted with proteins from soil bacteria called Bacillus thuringiensis (Bt) take on the proteins’ insect-killing powers. Crops grown from those seeds are then protected from a specific pest, for example, a corn seed that won’t get devastated by the European corn borer.

In reviewing hundreds of studies, researchers say Bt seeds also lead to less insecticide being sprayed.

“Because we can now control certain major pest insects in the crop through this gene being expressed in the plant, that eliminates largely the need to spray insecticides to do the same job,” according to entomologist Steve Naranjo of the U.S. Department of Agriculture’s Arid-Land Agricultural Research Center in Maricopa, Arizona.

He added that when insecticides are sprayed on Bt crops, they are typically used less frequently and in a more targeted manner, meaning beneficial insects and spiders are spared.

Bt crops have been grown on more than 1 billion acres worldwide. Naranjo said another ancillary effect is that many fields planted with traditional seeds that are adjacent to ones with Bt crops have also seen a reduction in problem pests.

“The economic benefits were as great for people who didn’t buy the technology as those who did,” Naranjo said, “in terms of controlling that insect pest.”

But Naranjo and other entomologists caution that insects are adaptable and can develop resistance to even the best tools.

“Eventually, over time, I think the insects will win,” said Iowa State University entomologist Erin Hodgson, who was not involved with the study. “In some cases, like corn borer, it has worked really well. In other cases, like corn rootworm, it hasn’t held up as strongly.”

Hodgson recommended that farmers continue to use an integrated crop management program with genetically engineered seeds, crop rotation and targeted uses of insecticides.

Overall, she said the correlation between Bt seeds and reduced dependence on broad spectrum sprayed-on insecticides also helps pollinator health because it results in less upheaval to the natural ecosystem.

And it may benefit humans as well.

“I’d personally rather eat, like, a sweet corn that has Bt than that has been sprayed 10 times with a synthetic insecticide,” Hodgson said. “I feel like it’s better for my health, too.”

Follow Amy on Twitter: @AgAmyInAmes

Amy Mayer is a reporter based in Ames